Friction coupling for change gears



April 1.3, 1937.l H. RAMBAUSEK 2,077,058

i l FRICTION COUPLING FOR CHANGE GEARS Filed May 16, 1935 3 Sheets-Sheet l CIJ 2,7 9 6 49 l 'Z8 z5 f. :D :D

April 13 1937- H. IRULWHBALISEK 2*,077-,058

FRICTIoN COUPLINQ FOR CHANGE GEARs Filed Mayl, 1935 3 Sheets-Sheet 2 /N VEA/Tak ffl/s0 KAH'BA 155K ATTORNEY April 13, 1937. H. RAMBAUSEK I 2,077,058

- FRICTION CUPLIN? FOR CHANGE GEARS Filed- May 16, 1955 .'5-SheetS-Sheet I5 INVENToR .ai-yq gsgambauses;

Patented Apr.- 13, 19137 UNITED STATES PATENT oFEicE..

Application May 16, 1935, Serial No. 21,765

, In Germany December 30, 1933 14 Claims. (Cl. 'I4-358) My invention relates to friction couplings for change gears and more particularly to friction couplings for change'gears' in which changing over can be carried out without an interruption of the transmission of power. This is obtained by'provlding a plurality of gears between the driving and driven shafts, each gear being associated with a coupling. In operation one of the v gears is put in by engaging the coupling assoelated therewith. For changingv over to anot r gear the coupling associated therewitha is engaged the rst gear being automatically thrown out as soon as the power is transmitted by the other gear. .0n the other hand the iirst gear is v automatically put in when the coupling assoablefone ci the members being aidally displace- '30 able by externally operated means while the auial position of the other member is controlled in response to the direction of the force transmitted between said other .member andwthe gear associated therewith as such force changes its direc- .35 tion depending upon whether the said pther member or the associated fgear tends to overrun l the `gear orthe other member respectively. For instance the first memberV may be displaceable by hand, the other member being withdrawn 40 i'rom the first one when the direction oi the force' between said other member and the gear associated therewith isv reversed. y

Ina preferred embodiment of my invention the position of. the second, coupling member isfcoai-V .M trolled byE meansof an auxiliary member Aa1'- ranged for a. limited reciprocation between two end positions in response to the direction of the force between said second coupling member and the gear associated therewith. The reciproca- 50 tion of the auxiliary member may be limited by means ofv suitable stops.

The coupling according to my invention may be designed and arranged so as to be disengaged when the relative rotations 'of the 'driving and 5;, driven members are changed in a predetermined In the irictionpcoupling according tc my uwenmanner, for instance when the .speed of lthe driven member exceeds that oi the driving 'member or when the direction of the rotation of the driven member is reversed Other objects oi my invention will appear fromr 5 the following description and claims.

In the drawingsafllxed hereto and forming partvof this specification some embodiments of my invention are illustrated diagrammatically by way ot example. 10

In the drawings:

Fig. 1 is a side elevationpartly in section, of a two-speed gear comprising a friction coupling according to my invention. which is automatically disengaged when the high speed is put in. 15

Fig. 2 is a. cross-section of the device shown in Fig. l along the lines II-II.

Fig. 3 is a sectional elevation, similar to Fig. 1, ci another embodiment of my invention, the coupling being automatically disengaged when the rotation of the driven member is reversed.

Fig. i is e. sectional elevation of a third embodiment of my invention, the driven shaft and the second gear for driving the driven coupling member being not shown. This coupling is automatically disengaged when the driven member rotates at a higher speed than the driving member and may be re-'engaged'by hand after such a disengagement.

Fig. 5 is a sectional elevation, similar to Fig. 4, 30 of a fourth, electrically operated embodiment the operation of which is independent of the direction of rotation of the driving member.

Fig. 6 is a cross-section of the device shown in Fig. 5 alongfthe lines JI-VI. ,/"f 35 Figs. 5a. and 6o are sectional .elevation and front view respectively of a modication of the switching means of an embodiment. according to Fig. '1 is a wiring diagram of the electrical cir- 40 cuit associated with the device shown in Fig. 5. Fig. t is a side elevation ci a two-speed gear with airiction clutch asshown in Fig. 5.

Referring now to the drawings and rst to Fig.

1, i is a driving shaft running in bearings 2 and 3. 45 t is a toothed wheel secured to the .shaft i. t is the driving member of a frictionV coupling the drivenmember of which is designated'by t. The driving member t is arranged axially displace--A able on the shaft i so as'to rotate therewith. 50 The driving member E is provided with a lgrorvved collar l engaged by the forked end 8 of a double-armed lever t fulcrumed at iii. The outer end il of the lever 9 may be moved to and fro in the direction ci the arrows i2 so as to 55 axially displace the driving coupling member 5 on the shaft I thereby engaging and disengaging the driven member 6. The driving and driven coupling members engage each other with conically shaped friction surfaces as will be seen from Fig. 1. I3 is a sleeve arranged loose, but axially undisplaceable on the shaft I and provided near its left hand end with a circular flange I4. The driven coupling member is mounted axially displaceable on the upper portion of the sleeve |3 so as to rotate therewith. I5 is a helical spring interposed between the driven coupling member 6 and the ange |4 of the sleeve I3. I6 is another sleeve arranged loose, but axially undisplaceable on the shaft I adjacent to the sleeve I3. The right hand port'ion of the sleeve I6 is provided with a horizontal flange I1 the inner surface of which is toothed. 'Ihe left hand portion of the sleeve I6 forms a transmission member or toothed wheel I8 engaging two other transmission members or toothed wheels |9 and 26 splined to the driven shaft 2| and to a lay shaft 22, respectively. The' bearings of the driven shaft 2| are not shown,

` circular flange I4v of the sleeve I3, respectively.

The right hand portions 29 of the shafts 28 are threaded at a high pitch and engage correspondingly threaded bores provided in the driving coupling member 6. 36 is a toothed wheel arranged loose on the lay shafty 22 so as to engage the toothed wheel 4. 'I'he wheel 36 is provided 4 with coupling dogs 3| adapted for engagement Witha coupling member 32v arranged axially-dis placeabie, but unrotatable on the lay shaft 22 and provided with dogs 33 and a grooved collar 34 engaged by the forked end 35 of an actuating lever 36 fulcrumedY at 31 vso that the coupling member 32 may be brought into and out of engagement by reciprocating the end 38 of the lever 36 in the direction of the arrows 39.'

. 'Ihe shaft I is driven by an engine (not shown) or the like in the direction of the arrow 46 (Fig. 2). In order to drive the driven shaft 2| at a low speed the friction coupling is brought to engagement by axially displacing the driving mem- .ber 5 by means of the lever 9 so that all paris occupy the positions shown in Fig. 1, shaft 2| being driven from shaft I through the coupling members 5,6, shafts 29, sleeve I3, dogs25, 26, sleeve I6 and wheels I8, I9. In order to change over from a low speed to a high one the coupling member 32 is brought to engagement with the toothed wheel 36 by rocking the lever 36. Then the speeds of the wheels I8, I9 and the shaft 2| will be increased owing to the dimensions of the toothedA wheels 4, 36, 26 and I8. In consequence ,thereof'the sleeve I6 is angularly displaced with respect to the sleeve I3 to an extent determined by the lost motion existing between the dogs 25 l and 26. 'By the angular displacement of the sleeves with/respect to each other the pinions21, the shafts 28 of which are mounted in the ange I4 of the sleeve I3, are rotated and impart an axial displacement to the driven coupling mein- Y ber 6 against the force of the spring I5 by the rotation of the threaded extensions 29 of the pinion shafts so that the friction coupling will be disengaged. When it is desired to change back to the lower speed the coupling member 32 is disengaged so as to occupy the position shown in Fig. 1, so that energy is no longer transmitted to the toothed wheel I8 'through the wheels 36 and 26. Thus the speed of the sleeve I6 will decrease while the tensloned spring I5 tends to expand. Due to the high pitch of the threads of the extensions 29 the spring I5 may expand.A

bshaft 2| the friction coupling may be disengaged by withdrawing the driving member 5 by means of the lever 9.

It is to be understood that the holding force of the friction coupling is practically independent of the value of the torque to be transmitted since the amounts of the relative angular displacement of the sleeve!l and of the axial displacement of the driven member 6 are determined by the engagements of the dogs 25 and 26 operating as stops for 'limiting the reciprocating movement of the sleeves and the driven member. Thus an increase of torque cannot cause an increase ofthe axial displacement of the driven coupling member or of the frictional engagement of the coupling members.

Referring now to Fig. 3 the device shown in this ligure substantially corresponds to that shown in Fig. 1 excepting two modifications. The first modiflcation consists in that a multiple disc coupling is provided instead of the conical friction coupling shown in Fig. 1. The inner discs 4I are secured to a member 42 splined to the driving shaft while the outer discs 43 are secured to the driven coupling member 6. I'he driving coupling member 5 is arranged so as to exert in its left hand position a clutch pressure so that the coupling is engaged. 'I'he other modication resides in that the automatic disengagement ofthe friction disc coupling takes place on a reversal of the direction of the rotation of the sleeve I3. In order to accomplish this .the circular -ange I4 of the sleeve I3 isexternally toothed dogsv 4,4 which may be engaged by the dogs 45 of a coupling member 46 arranged axially displaceable on the lay shaft 22 to the righthand end of which the toothed gear 36 is splined which engages an intermediate toothed wheel 41 meshing with the toothed wheel 4 splined to the driving shaft I.

The operation of this device is substantially the same as that of the device shown in Fig. 1 except that by an engaging of the coupling member 46 the rotation ofthe driven shaft is reversed. This device is particularly useful in connection with machine tools for driving reciprocating members for which the maintenance of defifnite reversing or turning points is required.

' It is to be understood that instead ofthe dog couplings 32, 45 shown in Figs. l and 3, friction couplings may be provided, if desired.

:Referring now to Fig. 4 in which the driven and layJ shafts and the toothed wheels mounted 011 them are not shown the friction coupling is normes designed' as a'multiple disc coupling similar to that shown in Fig. 3 and comprisesV thedriving member 5 axially displaceablysecured to the driving shaft I and inner and outer discs 4I, II

secured` to the member 42 andthe driven coupling member .6, respectively. .l` 5l is 'a helical spring interposed between the driving member 5 and the member l2 splined tothe shaft I. In

this embodiment the driven member l is direct- 1y connected to the sleeve It by means of a highpitch thread Il allowing a limited angular reciprocation of the sleeve I6 and the driven member 8 with respect to each other by which the driven member 6 is axially displaced in order to engage or disengage the coupling. 52 are helical-springs arranged inclined in suitable recesses 'provided in theslee'e l I Iv and the driven member i, r'- spectively. 53 is a ring mounted axially displaceable, but unrotatable on the shaft AI and connected to the driving member i by means of` helical springs 5l arranged in suitable recesses of the-ring and the driving member, respectively. Bl 'is another ring securedagainst rotation by means of an extension Vl engaging a grove 51 arranged parallel to the shaft- I. 5l is a roller rotatably mounted on a pin 59 projecting from the side wa.ll of`V the ring 55. 6l is a toothed wheel loosely mounted on the shaft I the hub of which is provided with an' extension 6 I engaging the interstice between the shaft I and the ring 55. At its left hand surface the wheel 60 is provided withan inclined .o curved cam A 'surface 62 engaging the roller 53. i! is a toothed wheel meshing with the wheel 6l. ,El is a hand- .operated wheel mounted on the shaft Si of the wheel 53. .If desired, `a plurality, forinstance three rollers 58 may be provided cooperating with multiple disc coupling inserted between. the coupling members 5 and 6 may be brought to en' Isagement by screwing the ring l5 Ato the left. It is to be understood that even at a slight pressure exerted by the member 5 on the discs 4I, 4I the Adrive'n'coupling memberv 6 in the event that it is not in its coupling position will be rotated in such a direction that the friction between the discs Il', 43 will be increased. This'motion will be aided by the springs 52 acting in the direction of the thread 5I. When the driven coupling mem- .be'r 6 hasreached its coupling position the springs il aretensioned an extent suflicient :for the transmission of* the torque.. When the toothed .wheel I8 forming part of the sleeve II is driven at a 'higherlfspeed than that" of the driven shaft I it will be screwed along the thread il so that the multiple dis'e'coupucg wm be automatically v disengaged. So far the operation is 'substantially the same as that of thcembodimefnts heretofore described. The device shown in Fig. 4,'howe'ver,v

differs from these embodiments ingthat aftersuch an automatic disengagement' the coupling may be re-engaged at will by'rotating the-hand wheel. Bl further so as to screw tothe left the rings 5I.'

5.3 and the member 5 until the multiple disc Vcoupling is re-engaged. A device'of this kind is particularly useful in connection with self-propelled vehicles in which an automatic disengagement oi the friction couplingvwill occur notonly when'the driver changes over from a lowv speed to a high one but also when the vehicle runs on a sloping road. In such cases'it is desirableto use'the engine of the car as a brakc'but in order to do so it is necessary to reengage the friction coupling which can be done in the manner describe y In the embodiments described heretofo'fe the` \inembers of the coupling are actuated'by mechanical means. If desired, however, instead of mechanical means hydraulic, pneumatical or electric means may be used. An embodiment of my in- Vvention iii-which electromagnetic means are provided for theautomatic disengagement of the coupling is shown vin Figs. 5 to '1. a

In the embodiment shown in Figs. 5 to 'l an automatic disengagement of the friction coupling takes place whenever the driven coupling member rotates at a higher speedthan the driving coupling membeni In con A nctionto the embodiments illustrated in Figs. 1f.to4 the automaticl disengagement isl independent from' the direction of the rotation of the dri shaft. Thus the device shown in Figs. 5 to '1 may be Y advantageously used in transmission with a plurality oi speeds .for the forward as weil laszfor the returnidrive particularly in consideration of the fact that it allows to change over without interrupting the transmission of power The construction of the right'hand portion o the coupling including the driving coupling member I, the multiple disccoliplingll, 41; 43 and the driven. coupling member 8 corresponds substantially tothe embodiment shown in Fig. 3.

.The connections, however, between the sleeves I I, I3 and the driven coupling vmember 6 are modied in the manner now to be described. 10.

. are helical springs inserted between the sleeve I3 land the driven coupling member 6 which tend to. hold thedriven member in its coupling position. The sleeve I I and the driven member 6 both consist of magnetic material such as soft iron. 1I is a current winding arranged in a suitable groove of the driven coupling member. This currentwinding will be energized in the manner described hereinafter when the speed of the driven member tends to exceed that of V.the driving member. Then a magnetic iiux will be produced by which the coupling member E is drawn to the leftv against lthe force of the springs 1l so that the multiple discl coupling will be disengaged.

One terminal of the current winding 1I is connectedto a slip ring 12 which is mounted insulated on the surface of the flange Il of the sleeve Il and is in contact with a slide contact 13. The sleeves and I6 are provided with dogs .25 and Il operating in the s ame manner as more fully described in` connection with Figs. 1 and 2 except that they are provided Ywith contact members-for closing and interrupting the circuit of the cur'l rent winding 1I The other terminal of the winding 1I is connected to acontact member 'Il 60 mounted insulated on one of the dogs ofthe sleeve Il. The dogs 26 of the sleeve I6 are provided with contact members 15 and 16, respectively. which in are connected to` slip rings' y.

. 11 and 1l, respectively, which are mounted insu- 6'5 lated on the sleeve IG. 'Il and 80 are contacts/ sliding on the slip rings 11 and 18, respectively," which are connected to stationary contact Aseg- V ments Il.A I I, respectively, forming part' o'f a l two-position switch the movable? contact I3. of i y Fig. 8 shows a transmission with'a clutch as` 75 illustrated in Fig. 5. An electromotor 81 is shown as the power source driving shaft It is to be understood, however, that any other suitable engine may be used instead of an electromotor. 'Ihe movable contact 83 may be connected to the shaft 86 of the ontroller drum (not shown) as conventionally used for controlling an electromotor so that contact 83 willI be in contact with one of the segments 8|, 82 according as the motor is controlled so as to supply forward or return drive. If another type of engine is employed, contact 83 may be connected with any suitable member controlling the engine.

In operation the switch is normally closed. As will be seen from Fig. l one of the slide contacts 19, 80 and the slip rings 11, 18 will be connected to the positive terminal of the current supply 84 when the movable contact 83 is in contact with one `of the contact segments 8|, 82. Be it assumed that during a forward drive the movable contact 83 is in contact with the segment 82 While during a return drive the movable contact 88 is in contact with the segment 8 i Thus during a for- 'Ward drive the contact member 16 will be connected to the current supply while during a return drive the contact member 15 will be connected to the current supply. When during a forward drive the coupling members rotate at the same speed, power being transmitted through the friction coupling, the relative positions of the sleeves i3 and I8 will be that shown in Fig. 6 in which contact member 14 is in contact with contactmember 15. In thisl position no current will flow through winding 1| since the circuit is interrupted at the contact segment 8|, movablevcontact member 83 being in contact with segment 82. Whenduring a forward drive the sleeve i6 is acceleratedas more fully described in connection with Fig. 1 the relative positions of the sleeves I8 and I3 will be changed so that contact member 14 will strike contact member 16. containing winding 1| will beclosed, this circuit including contacts 14, 16, slip rings 18, sliding contact 80, contact segment 82, movable contact 83, current supply 14, switch'85, sliding contact 13, slip ring 12 and currentwinding 1|. In consequence thereof the current Winding is energized and causes a disengaging of the friction coupling as described above.

During a return drive contact member 14 is in contact with contact member 16 when the coupling members rotate at the same speed. The current winding 1|, however, is not energized because in this case movable contact 83 is in contact with contactrsegment 8|, andout oi.' contact with segment. When during a return drive sleeve i8, respectively.

sleeve I6 is driven atI a higherspeed contact member 14 Ywill strike contact 15 and the winding 1| will be energized, the circuit includingbesides contacts 14 and 15 the contact segment 8| and the movable contact 83. l

1f lt is desired tb re-engage the coupling after an 'automatic disengaging, switch 85 may be opened. Besides this switch 815 may be used for bringing the driven coupling member- 6 in coupling position for starting purposes in the event thatthe winding 1| is energized at the moment of starting. Y

If desired-the switching devices 14, 15, 16 may be connectd to the driving lshaft and to the Although the relative movement between the shaft and the sleeve i6 is not limited th. operation of the switching members 14, and 18 if connected to these parts Then a circuitl may be rendered dependent on the relative movement of these parts by means of frictional switches or the like.

In the arrangement ofl Figs. 5a and 6a the switching devices 15 and 16 are connected to the driving shaft by means of a friction plate pressed against-a' collar 8| by means of a spring 92, and the contact member 14 is carried by gear I8 which is integral with sleeve |6. The parts 14, 15, 16 are connected with the slip rings 12, 19, 80 as in the Wiring diagram of Fig. '1.

It should be understood that instead of a lever other devices, for instance hand-operated electromagnetic means may be provided for operating vthe driving coupling member 5.

I wish it to be understood that I do not desire to be limited to the exact details of construction shown and described for obvious modifications' third member, externally operated means for displacing one of said coupling members, means in connection with said other coupling member and said third member for transmitting rotative forces between these last mentioned members, and adapted to permit a limited relative'rotation of these members, and means rotatable with one ofthe last mentioned members and responsive to their relative rotation for axially displacing said other coupling member.

2. A friction coupling 'for changeJ gears comprising a driving coupling member, a driven coupling member, a rotatable auxiliary member, a gear member, said members being coaxially arranged, externally operated means for axially displacing one of said coupling members, said other coupling member being axially displaceable in relation to and connected for rotation with said auxiliary member, said auxiliary member being arranged for a limited rotation in relation to said gearmember between two end positions, means rotatable with said auxiliary member and responsive to the relative movement betweensaid auxiliary member and said gear member for controlling the axial position of said other coupling member.

3. A friction coupling for change gears comprising a driving coupling member, a driven coupling member, a rotatable auxiliary member, a gear member, said members being coaxially arranged, externally operated means for axially displacing one of said coupling members, said other coupling member being axially displaceable in relation to and connected for rotation with said auxiliary member, said auxiliary member being arranged for a limited rotation in relation to said gear member between two end positions, means rotatablew with vsaid auxiliary 'member and .responsive to the relative movement between said auxiliary member and said gear member for controlling the axial position of said other coupling member, said controlling ineens comprising a' -high' pitch threaded connection between said auxiliary member and said other coupling member.

4. A friction coupling for change gears comprising a driving coupling member, a driven coupling member, a rotatable auxiliary member, a gear member, said members being coaxially arranged, externally operated means for axially displacing one of said coupling members, said other coupling member being axially displaceable in relation to and connectedfor rotation with. said auxiliary member, said auxiliary member being arranged for a limited rotation in relation to said gear member between two end positions, means rotatable with said auxiliary 5. A friction coupling for change gears comprising `a driving coupling member, a driven `coupling member, a rotatable auxiliary member,

0 a gear member, said members being coaxially arranged, externally operated means for axially displacingone of said coupling members, said other coupling member being axially displacev able in relation to and connected for rotation with said auxiliary member, said auxiliary member being arranged for a limited rotation in relation to said gear member between two end positions, means rotatable with saidv auxiliary member and vresponsive to a change of the direction of the force transmitted between said auxilv,lary member and said gear member for moving said auxiliary member from one end position to the other one, electromagnetic means in connection with said other coupling member for controlling the axial position of the other member, switching means connected to said auxiliary member for connecting and disconnecting said electromagnetic means to a current supply.

6. A friction coupling for'change gears comprising a driving coupling member,Y a driven coupling member, a rotatable auxiliary member, a gear member, -said members being coaxiallyarranged, externally operated means forl axially displacing one of. Vsaid coupling members, said other coupling member being axially displaceable in relation to and connected for rotation with said auxiliary member, said auxiliary member being arranged for a limited rotation in relation to said gear member between two end positions, means rotatable with said auxiliary member and responsive toa change of the direction of the, force transmitted between said auxiliary member and said gear member for moving said auxiliary member from one end position to the other one, electromagnetic means in connection with said other coupling member for conprising a driven coupling member, a driving coupling member adapted to drive the driven coupling member, additional means` apart from said driving member for driving said driven coupling member, externally operated means for axially displacing saiddriving coupling member, an auxiliary member connected for rotation with said driven coupling member, a gear member arranged for a limited rotation with said auxiliary member between two end positions, and means rotatable with saidfauxiliary member and responsive to the direction of the force transmitted between said auxiliary member and s aid gear member for controlling the axial position of said other coupling member so as to. disengage the coupling when said additional driving means impart to said driven vmember a speed exceeding that of said driving member.

`8. A friction coupling for change gears comprising a driven coupling member, a drivingI coupling member adapted to drive the driven coupling member, additional means apart from said driving member fordriving said drivenlcoupling member,. externally operated means for axially displacing one of said coupling members, an auxiliary member connected for rotation with said driven coupling member, a gear member ar` ranged for a limited rotation with said auxiliary member between two end positions, means rotatable with said auxiliary member and responsive to the direction of the force transmitted between said auxiliary member and said gear member for controlling the axial position of said other coupling member so as to disengage th coupling when said additional driving means impart to said driven member a speed exceeding that of said driving member, and externally operated means for axially displacing one` of said coupling members whereby the engagement of said driving and driven member may be re-establis'hed after the disengagement of the coupling by said direction responsive means.

9. A friction clutch comprising a driving cou- `pling member and a driven couplingmember, each of said coupling members being individually movable in axial direction into a position of disengagement and into a position for engagement,

in combinationwith a change gear transmission including a rotatable transmission member with which said clutch is associated, externally operated means for axially moving said driving coupling member, a lost motion connection between said driven coupling member and said transmission member, whereby rotative forces may be transmitted between said two last mentioned members in either direction, and means connected to ati least one of said two last mentioned members, and responsive to the direction of the forces transmitted'th'rough said lost motion connection for controlling the position of said driven coupling member. l

10. A friction clutch comprising a driving coupling member and a driven coupling member, each of said coupling members being individually movable in axial direction into a position of. disengagement and into a position for engagement, in combination with a change gear transmission including a rotatable transmission memberwith which said clutch is associated, externally operated means for axially moving said driving coupling member, an auxiliary member connected for rotation with said driven coupling member, a lost motion connection between said driven coupling member and said transmission member,

whereby rotative forces may be transmitted be-4 tween said two last mentioned members-in either direction, and means in connection with said auxiliary member and said transmission member and responsive to the direction of the forces transmitted through said lost motion connection for controlling the position of said driven coupling member 11. A friction clutch comprising a driving coupling member and a driven coupling member, 10 each of said coupling members being individually movable in axial direction into a, position of disengagement and into a position for engagement, in combination with a change gear transmission including a first rotatable transmission member l5 with which said friction clutch is associated, a

second transmission member connected for rotation with said flrst transmission member, externally operated means for axially moving said driving coupling menber, a lost motion connec-l tion between said driven coupling member and said iirst transmission member, whereby rotative forces may be transmitted between said two last mentioned members in either direction, and means connected to at least one of said two last mentioned members, and responsive to the direction of the forces transmitted through `said lost motion connection for controlling the position of said driven coupling member, whereby said driven coupling member is being moved into its position of disengagement when said first transmission member driven by said second transmission member overruns said driven coupling member.,

12. A friction clutch comprising a driving coupling member and a driven coupling member, each of said coupling members being individually movable in axial directionI into a position of disengagement and into a position for engagement, in combination with a change gear transmission including a rotatable transmission member in coaxial arrangement with said driven coupling member and being unmovable in axial direction, externally operated means for axially moving said driving coupling member, a high pitch threaded connection coaxially arranged between said driven coupling member and said transmission member for transmitting rotative forces between said two last mentioned members, said thread having such a direction as to move said driven coupling member into its position of disengagement when said transmission member overruns said driven coupling member, and resilient means bearing against said driven coupling member and tending to move it into its position for engagement.

, 13. A friction clutch comprising a driving coupling member and a driven coupling member, each of -said coupling members being individually movable in axial direction into a position of disengagement and into a position for engagement, in combinatiowith a change gear transmission including a rotatable transmission member with which said clutch is associated, externally operated means for axially Ymoving said driving coupling member, electromagnetic means in connection with said driven coupling member for moving it in axial direction, a lost motion connection between said driven coupling member and said transmission member, contact means rotativelyA connected with said driven coupling member, and counter-contact means rotatively connected with said transmission member for connecting said electromagnetic means to a current supply, whereby said electromagnetic means are being energized to move said driven coupling member into its position of disengagement when said transmission member overruns said driven coupling member.

14. A friction clutch device as claimed in claim 13 in which said contact means is provided in duplicate and said counter-contact means is so arranged as to engage one of sa'id contact means -when said transmission member tends to overrun said driven coupling member in one direction of rotation, and as to engage the other contact means when said transmission member tends to overrun said driven coupling member in the other direction of rotation, external switching means being provided for rendering inoperative one or the other one of said contact means.

HUGO RAMBAUSEK. 

